1. Field of the Invention
This invention relates to a mechanical linkage designed to act between a controlling mechanism fixed relative to one machine part (which may be the handlebars or equivalent of a bicycle) and a controlled mechanism fixed relative to another part of the same machine, which second part may be the frame of the bicycle. When the machine is a bicycle, the “controlling mechanism” usually includes some form of lever whilst the “controlled mechanism” is usually a brake or gear.
2. Description of the Prior Art
Because the front wheel of a bicycle needs to swivel relative to the frame, the linkage must accommodate this swiveling movement. Patent specification FR571408 describes one way in which this can be done for a single rear brake. Other known techniques use Bowden cables which will flex sufficiently to allow some rotation of the handlebars and associated parts; but are unable to accommodate unlimited rotation of the front wheel support as is required on some so-called “freestyle” bicycles. To meet this problem, there have been many proposals for rotating couplings between two parts of a Bowden cable such as described in patent specifications U.S. Pat. No. 5,992,869 and GB 2351327.
These known rotatable couplings are all unable to serve more than one mechanism to be controlled on the fixed part of the bicycle frame. This is a serious problem because a large proportion of bicycles have at least two such mechanisms e.g. a rear brake and a gear, or a rear brake and two gears.